In the poster image, a soldier with piercing blue eyes sits on a log next to a small campfire, enduring the falling snow. The shoulders of his blue regimental are torn, he has no greatcoat, one knee of his breeches is torn out, the other is patched. He wears a red scarf around his head and neck under his tricorned hat. The barrel of his musket is wrapped in fabric, probably to keep the snow out, and a knife or bayonet is in a sheath at his hip, next to his cartridge box. What appears to be a wooden canteen is around his neck. And on a forked stick he grills a thin piece of something over the fire - I suspect it is meant to be shoe leather, as he holds another piece in his hand, although it could simply be thin cuts of meat. The men famously boiled the leather of their shoes in an attempt to stave off starvation. What food was available was usually just meat and flour - no vegetables, no bread.
These stories would have been well-known in the 1940s, part of the American mythology education that passed for history at the time. By comparing the soldiers of the American Revolution to the soldiers of the Second World War, this propaganda poster is reminding the men of the privileges they have in provisioning, and encouraging them to avoid waste, while hearkening back to the stamina and bravery of the men at the time.
Other propaganda posters, like these, encouraged troops to conserve food because the folks back home were going without so they could have enough.
While the nation today continues to recover from an enormous winter storm, with widespread power outages, it seemed apt to revisit Valley Forge. Read more about the food situation at Valley Forge in 1777-78.